Koocanusa expected to remain low this summer

The high water level in Lake Koocanusa this summer will be significantly lower than normal due to an abnormally dry winter and spring.

According to a media release from the U.S. Army Corps of Engineers, it has been one of the driest years recorded for the Kootenai River Basin. Extremely low spring precipitation combined with well below average winter snowpack and runoff will keep the Northwest Montana reservoir significantly lower than normal this summer, the release states.

Officials said that the reservoir elevation is projected to peak between 2,432 to 2,437 feet — potentially as much as 22 feet below the typical targeted peak pool elevation of 2,454 feet — and expected to occur in the first two weeks of August rather than late July.

“It has been a dry year overall,” said Logan Osgood-Zimmerman, U.S. Army Corps of Engineers’ upper Columbia River senior water manager. “We kept the reservoir nearly five feet higher at the end of December than in most years and then have been operating on minimum flows for much of winter and spring to try and conserve water.”

Currently, Lake Koocanusa is on track to have the fourth lowest inflow volume since 1960.

The Kootenai basin snowpack averaged about 70 percent of normal all winter. In February, inflow into Lake Koocanusa was the lowest monthly inflow volume ever measured between 1960-2019. May precipitation was 36 percent of normal, and June precipitation has been 45 percent of normal, thus far.

The Corps’ swim platform at Souse Gulch will likely not be available for use because of low lake levels and access to private docks and marinas may be impacted.

Libby Dam discharge gradually decreased from 20,000 cubic feet per second to 7,000 cfs from June 20-25 and is expected to remain at that level through August before reducing to 6,000 cfs in September.